The Evolution of Desire
by Meicdon13
Summary: ONESHOT :: Seiten Taisei is intrigued by Hakkai's youkai form. :: Seiten Taisei x youkai!Hakkai


**Pairing: **Seiten Taisen x demon!Hakkai (prompt : shadows)**  
Disclaimer: **_Saiyuki_ does not belong to me. I merely borrow the boys.**  
****Warnings: **A lot of blood from violence and fighting between demon!Hakkai and Seiten Taisei.**  
Author's notes: **I'm not really sure what I've done to this fic…And I hope I managed to incorporate the prompt. Beta-ed by the lovely **xcerpted**. Written for **2light4dark **over at the _Saiyuki _**valentinesmut LJ Community**.

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**THE EVOLUTION OF DESIRE **

He watches the healer from inside his prison. Whenever he's bored with reliving his memories of freedom, Seiten Taisei peers out through eyes that-are-not-his and watches Hakkai. Watches the way he moves and the grace and utter _control_ that accompanies each action. The way Hakkai fights. The way he walks. Smiles. Talks.

Seiten Taisei especially likes watching Hakkai at night. When the Sanzo-ikkou is forced to camp outdoors, miles away from the nearest town, the itan watches the moonlight or firelight fall on Hakkai's features, creating shadows on the green-eyed man's pale skin. He likes the contrast of darkness and light on Hakkai's figure, likes how it makes the taller brunet seem deadly.

But watching can only do so much for someone. Soon enough, Seiten Taisei wants to run clawed fingers through dark brown hair, wants to see for himself if it's as soft as it seems. He wants to lick the slender column of Hakkai's neck, wants to taste the skin of the healer and nip it with his fangs. Seiten Taisei wants to taste Hakkai's blood on his tongue.

He doesn't care for the monk or the hanyou. They are interesting in their own right but they don't capture his attention the way Hakkai does. There is something absolutely _dangerous_ about the healer that intrigues Seiten Taisei; he feels that there is more to him than meets the eye.

One day, Seiten Taisei gets his chance to see what lurks beneath the taller brunet's calm exterior. His idiotic twinbrotherself and Hakkai have been imprisoned inside a gourd; their souls trapped while their bodies lie like corpses on a bed. It's his first time seeing Hakkai like this. Hakkai with his face grim and determined and scared and sort of sad in a way that he can't explain.

He watches as Hakkai reaches up to touch his ear, running his fingertips along the smooth metal of his power limiters. Seiten Taisei's golden eyes narrow as he watches those long fingers remove the limiters, one by one. They fall to the ground—appearing to be instantly forgotten by the brunet—and for a moment, Seiten Taisei looks at them. He almost misses the transformation.

It's breathtaking the way that Hakkai changes. The intricate vine tattoos that appear on his skin make Seiten Taisei want to trace a clawed fingertip along each green curling stem. He wonders if the vines also wrap around Hakkai's cock.

He simply watches as the youkai fights. The grace and beauty and control are still there, merely in a purer, _rawer_, more dangerous form. It's almost as if Hakkai is dancing.

When everything's over and the danger is gone, Seiten Taisei glares daggers at the power limiters as Hakkai clips them on again. Who would want to cage such strength? The itan clenches his hands. Probably the same people who don't want him to be free. He wonders why the healer can still have enough control of his body to wear his limiters again. He wonders why Hakkai would _want_ to put on his limiters.

After that moment, Seiten Taisei waits impatiently for the next opportunity to arise; another chance to see what he considers the _real_ Hakkai. The wild youkai that is almost as powerful as him, the one with the vines that crawl across his skin and a sleek destructive grace.

Seiten Taisei waits for days, for weeks, for months. He grows frustrated. His pacing makes Goku fidget and the monk hits himthem on the head with his harisen. Seiten Taisei wants to rip the human into shreds.

Then finally—blessedly, thankfully—he is free. The golden limiter falls from his forehead, clanging loudly on the ground as it hits. There are shouts and attacks come flying at him from all directions but he is the Great Sage Equal to Heaven and he easily evades them.

Gojyo goes down with a kick to the back of his head. Sanzo is next and as Seiten Taisei knocks him out, Goku shouts and tries to stop him but he is older and he forces his other half to be quiet, to let him have his turn, to let him control the body they share.

Hakkai is scared but Hakkai is also determined and Seiten Taisei licks his lips in anticipation for what is to come. He moves, avoids the hands that try to stop him and yanks off the limiters that adorn the green-eyed man's ear.

Before they even hit the ground, Hakkai has already finished changing. His claws rake down Seiten Taisei's arms, leaving bloody trails in their wake, his fangs nearly closing around the itan's throat. They wrestle and growl and tear at clothing. Vines wrap around Seiten Taisei's wrists and middle, trying to drag him off but the golden-eyed being has half a century's worth of frustration and he destroys the restraints as if they were nothing.

The itan grabs both of Hakkai's wrists in one hand, pinning them above the healer's head, his other hand ripping Hakkai's pants. Moonlight spills down over them, painting everything silver and black. Seiten Taisei focuses on the shadows that cover Hakkai's heaving body beneath him even as he forces the healer's legs apart, claws digging into the soft skin on the youkai's thighs.

A smirk curves Seiten Taisei's lips as he sees the lone vine tattoo making its way along Hakkai's cock. Then, he pushes in.

There is heat and tightness and _Hakkai _and the itan instantly pounds into the youkai. Hands are still clawing at his back, breaking skin and making blood flow, though he is not sure whether they're trying to hurt him or not. He tightens his grip on Hakkai's wrists and he thinks he might have broken something but he doesn't care.

The scent of blood is thick in the night air; from the unconscious bodies near them, from the blood flowing down Seiten Taisei's back and arms, from between Hakkai's legs, from the wounds the two of them inflicted each another.

It's like they're still fighting and Seiten Taisei leans down to sink his fangs into Hakkai's neck. He doesn't bite down hard enough to kill but with enough pressure to let the youkai know that his life is in the itan's hands.

Seiten Taisei orgasms when he sees their shadowy silhouette on the ground beside them, moving as if they were one entity. He lets himself fall on top of the youkai and he feels a mixture of blood and semen on his stomach. A cold circle of gold falls around his head and he realizes that Hakkai must have used a vine to get his limiter.

The shadows fall upon him and Seiten Taisei sinks into unconsciousness.


End file.
